Atmosphere

17 pages, 4600 KiB

Open AccessArticle

An Assessment of Stratospheric Intrusions in Italian Mountain Regions Using STEFLUX

by Paolo Cristofanelli, Piero Di Carlo, Eleonora Aruffo, Francesco Apadula, Mariantonia Bencardino, Francesco D’Amore, Paolo Bonasoni and Davide Putero

Atmosphere 2018, 9(10), 413; https://doi.org/10.3390/atmos9100413 - 22 Oct 2018

Cited by 4 | Viewed by 3667

Abstract

The Mediterranean basin is considered a global hot-spot region for climate change and air quality, especially concerning summer-time ozone (O₃). Previous investigations indicated that the Mediterranean basin is a preferred region for stratosphere-to-troposphere exchange (STE) and deep stratospheric intrusion (SI) events. [...] Read more.

The Mediterranean basin is considered a global hot-spot region for climate change and air quality, especially concerning summer-time ozone (O₃). Previous investigations indicated that the Mediterranean basin is a preferred region for stratosphere-to-troposphere exchange (STE) and deep stratospheric intrusion (SI) events. The Lagrangian tool STEFLUX, based on a STE climatology that uses the ERA Interim data, was hereby used to diagnose the occurrence of deep SI events in four mountain regions over the Italian peninsula, spanning from the Alpine region to the southern Apennines. By using near-surface O₃ and relative humidity (RH) observations at three high-mountain observatories, we investigated the performance of STEFLUX in detecting deep SI events. Both experimental and STEFLUX detections agreed in describing the seasonal cycle of SI occurrence. Moreover, STEFLUX showed skills in detecting “long-lasting” SI events, especially in the Alps and in the northern Apennines. By using STEFLUX, we found positive tendencies in the SI occurrence during 1979–2017. However, in contrast to similar studies carried out in the Alpine region, the negative long-term (1996–2016) trend of O₃ in the northern Apennines did not appear to be related to the SI’s variability. Full article

(This article belongs to the Special Issue Stratosphere–Troposphere Exchanges)

► Show Figures

Figure 1

13 pages, 1681 KiB

Open AccessArticle

Polycyclic Aromatic Hydrocarbons in PM_2.5 and PM_2.5–10 in Urumqi, China: Temporal Variations, Health Risk, and Sources

by Suwubinuer Rekefu, Dilinuer Talifu, Bo Gao, Yusan Turap, Mailikezhati Maihemuti, Xinming Wang and Abulikemu Abulizi

Atmosphere 2018, 9(10), 412; https://doi.org/10.3390/atmos9100412 - 22 Oct 2018

Cited by 13 | Viewed by 3209

Abstract

PM_2.5 and PM_2.5–10 samples were simultaneously collected in Urumqi from January to December 2011, and 14 priority polycyclic aromatic hydrocarbons (PAHs) were determined. The mean concentrations of total PAHs in PM_2.5 and PM_2.5–10 were 20.90~844.22 ng m⁻³ and [...] Read more.

PM_2.5 and PM_2.5–10 samples were simultaneously collected in Urumqi from January to December 2011, and 14 priority polycyclic aromatic hydrocarbons (PAHs) were determined. The mean concentrations of total PAHs in PM_2.5 and PM_2.5–10 were 20.90~844.22 ng m⁻³ and 19.65~176.5 ng m⁻³ respectively, with the highest in winter and the lowest in summer. Above 80% of PAHs were enriched in PM_2.5, which showed remarkable seasonal variations compared to coarse particles. High molecular weight (HMW) PAHs were predominant in PM_2.5 (46.61~85.13%), whereas the proportions of lower molecular weight (LMW) and HMW PAHs in PM_2.5–10 showed a decreasing and an increasing trend, respectively, from spring to winter. The estimated concentrations of benzo[a]pyrene equivalent carcinogenic potency (BaP_eq) in PM_2.5 (10.49~84.52 ng m⁻³) were higher than that of in PM_2.5–10 (1.15~13.33 ng m⁻³) except in summer. The estimated value of inhalation cancer risk in PM_2.5 and PM_2.5–10 were 1.63 × 10⁻⁴~7.35 × 10⁻³ and 9.94 × 10⁻⁵~1.16 × 10⁻³, respectively, far exceeding the health-based guideline level of 10⁻⁴. Diagnostic ratios and positive matrix factorization results demonstrated that PAHs in PM_2.5 and PM_2.5–10 were from similar sources, such as coal combustion, biomass burning, coking, and petroleum combustion, respectively. Coal combustion was the most important source for PAHs both in PM_2.5 and PM_2.5–10, accounting for 54.20% and 50.29%, respectively. Full article

(This article belongs to the Section Air Quality)

► Show Figures

Graphical abstract

28 pages, 17221 KiB

Open AccessArticle

Natural Ventilation of a Small-Scale Road Tunnel by Wind Catchers: A CFD Simulation Study

by Shanhe Liu, Zhiwen Luo, Keer Zhang and Jian Hang

Atmosphere 2018, 9(10), 411; https://doi.org/10.3390/atmos9100411 - 20 Oct 2018

Cited by 15 | Viewed by 6776

Abstract

Providing efficient ventilation in road tunnels is essential to prevent severe air pollution exposure for both drivers and pedestrians in such enclosed spaces with heavy vehicle emissions. Longitudinal ventilation methods like commercial jet fans have been widely applied and confirmed to be effective [...] Read more.

Providing efficient ventilation in road tunnels is essential to prevent severe air pollution exposure for both drivers and pedestrians in such enclosed spaces with heavy vehicle emissions. Longitudinal ventilation methods like commercial jet fans have been widely applied and confirmed to be effective for introducing external fresh air into road tunnels that are shorter than 3 km. However, operating tunnel jet fans is energy consuming. Therefore, for small-scale (~100 m–1 km) road tunnels, mechanical ventilation methods might be highly energetically expensive and unaffordable. Many studies have found that the use of wind catchers could improve buildings’ natural ventilation, but their effect on improving natural ventilation in small-scale road tunnels has, hitherto, rarely been studied. This paper, therefore, aims to quantify the influence of style and arrangement of one-sided flat-roof wind catchers on ventilation performance in a road tunnel. The concept of intake fraction (IF) is applied for ventilation and pollutant exposure assessment in the overall tunnel and for pedestrian regions. Computational fluid dynamics (CFD) methodology with a standard k-epsilon turbulence model is used to perform a three-dimensional (3D) turbulent flow simulation, and CFD results have been validated by wind-tunnel experiments for building cross ventilation. Results show that the introduction of wind catchers would significantly enhance wind speed at pedestrian level, but a negative velocity reduction effect and a near-catcher recirculation zone can also be found. A special downstream vortex extending along the downstream tunnel is found, helping remove the accumulated pollutants away from the low-level pedestrian sides. Both wind catcher style and arrangement would significantly influence the ventilation performance in the tunnel. Compared to long-catcher designs, short-catchers would be more effective for providing fresh air to pedestrian sides due to a weaker upstream velocity reduction effect and smaller near-catcher recirculation zone. In long-catcher cases, IF increases to 1.13 ppm when the wind catcher is positioned 240 m away from the tunnel entrance, which is almost twice that in short-catcher cases. For the effects of catcher arrangements, single, short-catcher, span-wise, shifting would not help dilute pollutants effectively. Generally, a design involving a double short-catcher in a parallel arrangement is the most recommended, with the smallest IF, i.e., 61% of that in the tunnel without wind catchers (0.36 ppm). Full article

(This article belongs to the Special Issue Recent Advances in Urban Ventilation Assessment and Flow Modelling)

► Show Figures

Figure 1

13 pages, 15586 KiB

Open AccessArticle

The Impacts of Smoke Emitted from Boreal Forest Wildfires on the High Latitude Radiative Energy Budget—A Case Study of the 2002 Yakutsk Wildfires

by Zheng Lu and Irina N. Sokolik

Atmosphere 2018, 9(10), 410; https://doi.org/10.3390/atmos9100410 - 19 Oct 2018

Cited by 7 | Viewed by 2979

Abstract

We examine the 2002 Yakutsk wildfire event and simulate the impacts of smoke aerosols on local radiative energy budget, using the WRF-Chem-SMOKE model. When comparing satellite retrievals (the Surface Radiation Budget (SRB) dataset) with model simulations, we found that the agreement is generally [...] Read more.

We examine the 2002 Yakutsk wildfire event and simulate the impacts of smoke aerosols on local radiative energy budget, using the WRF-Chem-SMOKE model. When comparing satellite retrievals (the Surface Radiation Budget (SRB) dataset) with model simulations, we found that the agreement is generally good, except for the regions where the model predicts too few clouds or SRB misclassifies strong smoke plumes as clouds. We also found that the smoke-induced changes in upward shortwave fluxes at top of atmosphere (TOA) vary under different burning and meteorological conditions. In the first period of the fire season (9–12 August), smoke particles cause a warming effect around 3 W/m², mainly through functioning as ice nuclei, which deplete the cloud water amount in the frontal system. At the beginning of the second period of the fire season (19–20 August), large amounts of pre-existing smoke particles cause a strong cooling effect of −8 W/m². This is offset by the warming effect caused by relatively small amounts of cloud condensation nuclei increases, which promotes the rain formation and depletes the cloud water amount. After the cloud decks are well mixed with smoke plumes (21–22 August), the first indirect and direct effects of smoke together lead to a cooling of −10 W/m². These results highlight the importance of meso-scale modeling efforts in estimating the smoke-induced changes in the radiative energy budget over high latitudes. Full article

(This article belongs to the Special Issue Radiative Transfer in the Earth Atmosphere)

► Show Figures

Figure 1

12 pages, 1448 KiB

Open AccessReview

Temporal Trends in Heat-Related Mortality: Implications for Future Projections

by Patrick L. Kinney

Atmosphere 2018, 9(10), 409; https://doi.org/10.3390/atmos9100409 - 18 Oct 2018

Cited by 26 | Viewed by 5354

Abstract

High temperatures have large impacts on premature mortality risks across the world, and there is concern that warming temperatures associated with climate change, and in particular larger-than-expected increases in the proportion of days with extremely high temperatures, may lead to increasing mortality risks. [...] Read more.

High temperatures have large impacts on premature mortality risks across the world, and there is concern that warming temperatures associated with climate change, and in particular larger-than-expected increases in the proportion of days with extremely high temperatures, may lead to increasing mortality risks. Comparisons of heat-related mortality exposure-response functions across different cities show that the effects of heat on mortality risk vary by latitude, with more pronounced heat effects in more northerly climates. Evidence has also emerged in recent years of trends over time in heat-related mortality, suggesting that in many locations, the risk per unit increase in temperature has been declining. Here, I review the emerging literature on these trends, and draw conclusions for studies that seek to project future impacts of heat on mortality. I also make reference to the more general heat-mortality literature, including studies comparing effects across locations. I conclude that climate change projection studies will need to take into account trends over time (and possibly space) in the exposure response function for heat-related mortality. Several potential methods are discussed. Full article

(This article belongs to the Special Issue Impacts of Climate Change on Human Health)

► Show Figures

Figure 1

15 pages, 6260 KiB

Open AccessArticle

The Identification of Iran’s Moisture Sources Using a Lagrangian Particle Dispersion Model

by Mojtaba Heydarizad, Ezzat Raeisi, Rogert Sori and Luis Gimeno

Atmosphere 2018, 9(10), 408; https://doi.org/10.3390/atmos9100408 - 17 Oct 2018

Cited by 25 | Viewed by 5322

Abstract

Iran has faced many water shortage crises in the past. Iran’s moisture sources for precipitation were identified by Lagrangian approach using the FLEXible PARTicle dispersion model (FLEXPART) v9.0 model. The results demonstrate that Iran receives its moisture from both continental and oceanic sources. [...] Read more.

Iran has faced many water shortage crises in the past. Iran’s moisture sources for precipitation were identified by Lagrangian approach using the FLEXible PARTicle dispersion model (FLEXPART) v9.0 model. The results demonstrate that Iran receives its moisture from both continental and oceanic sources. During the wet season, moisture uptake from the Arabian Sea, the Persian Gulf, and the Mediterranean Sea is dominant, while during the dry season, the role of the Red Sea, the Caspian Sea, and the Persian Gulf is intensified. Studying drought conditions by comparing 1-month, 6-month, and 12-month standardized precipitation index (SPI) with (E-P) values of oceanic and continental moisture sources (E stands for the evaporation and P the precipitation) using multiregression model demonstrates that among oceanic sources the Arabian Sea, the Persian Gulf, the Mediterranean Sea, and the Indian Ocean affect SPI values and among continental sources, moisture from bare grounds and cultivated lands influences SPI values during wet season. However, no correlation exists between oceanic and continental (E-P) and SPI values during the dry season. The results obtained by this study can be used by meteorologists and hydrology scientists for future water management programmes in Iran. Full article

(This article belongs to the Section Meteorology)

► Show Figures

Figure 1

25 pages, 3380 KiB

Open AccessArticle

Closing the N-Budget: How Simulated Groundwater-Borne Nitrate Supply Affects Plant Growth and Greenhouse Gas Emissions on Temperate Grassland

by Ralf Liebermann, Lutz Breuer, Tobias Houska, Steffen Klatt, David Kraus, Edwin Haas, Christoph Müller and Philipp Kraft

Atmosphere 2018, 9(10), 407; https://doi.org/10.3390/atmos9100407 - 17 Oct 2018

Cited by 6 | Viewed by 4086

Abstract

European groundwater reservoirs are frequently subject to reactive nitrogen pollution (N_r) owing to the intensive use of nitrogen (N) fertilizer and animal manure in agriculture. Besides its risk on human health, groundwater N_r loading also affects the carbon (C) and [...] Read more.

European groundwater reservoirs are frequently subject to reactive nitrogen pollution (N_r) owing to the intensive use of nitrogen (N) fertilizer and animal manure in agriculture. Besides its risk on human health, groundwater N_r loading also affects the carbon (C) and N cycle of associated ecosystems. For a temperate grassland in Germany, the long-term (12 years) annual average exports of N_r in form of harvest exceeded N_r inputs via fertilization and deposition by more than 50 kgN ha⁻¹. We hypothesize that the resulting deficit in the N budget of the plant-soil system could be closed by N_r input via the groundwater. To test this hypothesis, the ecosystem model LandscapeDNDC was used to simulate the C and N cycle of the respective grassland under different model setups, i.e., with and without additional N_r inputs via groundwater transport. Simulated plant nitrate uptake compensated the measured N deficit for 2 of 3 plots and lead to substantial improvements regarding the match between simulated and observed plant biomass and CO₂ emission. This suggests that the C and N cycle of the investigated grassland were influenced by N_r inputs via groundwater transport. We also found that inputs of nitrate-rich groundwater increased the modelled nitrous oxide (N₂O) emissions, while soil water content was not affected. Full article

► Show Figures

Graphical abstract

13 pages, 11496 KiB

Open AccessArticle

The Quasi-Biweekly Oscillation of Winter Precipitation Associated with ENSO over Southern China

by Qiaoyu Tong and Suxiang Yao

Atmosphere 2018, 9(10), 406; https://doi.org/10.3390/atmos9100406 - 16 Oct 2018

Cited by 3 | Viewed by 3618

Abstract

Using ERA-interim Reanalysis data and observational data, the intraseasonal oscillation of the winter rainfall in southern China is studied. The mean square deviation of daily precipitation is used to express precipitation variability, and winter precipitation variability over southern China is determined to be [...] Read more.

Using ERA-interim Reanalysis data and observational data, the intraseasonal oscillation of the winter rainfall in southern China is studied. The mean square deviation of daily precipitation is used to express precipitation variability, and winter precipitation variability over southern China is determined to be highly correlated with sea surface temperature (SST) in central and eastern tropical Pacific; the dominant period of the precipitation is 10–30 days, which reflects quasi-biweekly oscillation. Examination of 1000 hPa geopotential height suggests that key low-pressure systems affecting the intraseasonal precipitation come from Lake Baikal, but with different travel paths. In El Niño years, key low-pressure systems converge with other low-pressure systems and move southeastward until reaching South China, while in La Niña years, only one low-pressure system can reach southern China. Meanwhile, the explosive development of the low-pressure system is mainly caused by the joint effects of thermal advection and vorticity advection in El Niño, and only vorticity advection accounted for the dominant status in La Niña. Multiscale analysis shows that the meridional distribution of intraseasonal circulation plays an important role on the thermal transmission and brings strong warm advection from low latitudes to high latitudes in El Niño. Full article

(This article belongs to the Section Meteorology)

► Show Figures

Figure 1

26 pages, 2054 KiB

Open AccessArticle

Development of a Regression Model for Estimating Daily Radiative Forcing Due to Atmospheric Aerosols from Moderate Resolution Imaging Spectrometers (MODIS) Data in the Indo Gangetic Plain (IGP)

by Shreemat Shrestha, Murray C. Peel and Graham A. Moore

Atmosphere 2018, 9(10), 405; https://doi.org/10.3390/atmos9100405 - 16 Oct 2018

Cited by 3 | Viewed by 4994

Abstract

The assessment of direct radiative forcing due to atmospheric aerosols (ADRF) in the Indo Gangetic Plain (IGP), which is a food basket of south Asia, is important for measuring the effect of atmospheric aerosols on the terrestrial ecosystem and for assessing the effect [...] Read more.

The assessment of direct radiative forcing due to atmospheric aerosols (ADRF) in the Indo Gangetic Plain (IGP), which is a food basket of south Asia, is important for measuring the effect of atmospheric aerosols on the terrestrial ecosystem and for assessing the effect of aerosols on crop production in the region. Existing comprehensive analytical models to estimate ADRF require a large number of input parameters and high processing time. In this context, here, we develop a simple model to estimate daily ADRF at any location on the surface of the IGP through multiple regressions of AErosol RObotic NETwork (AERONET) aerosol optical depth (AOD) and atmospheric water vapour using data from 2002 to 2015 at 10 stations in the IGP. The goodness of fit of the model is indicated by an adjusted R² value of 0.834. The Jackknife method of deleting one group (station data) was employed to cross validate and study the stability of the regression model. It was found to be robust with an adjusted R² fluctuating between 0.813 and 0.842. In order to use the year-round ADRF model for locations beyond the AERONET stations in the IGP, AOD, and atmospheric water vapour products from MODIS Aqua and Terra were compared against AERONET station data and they were found to be similar. Using MODIS Aqua and Terra products as input, the year-round ADRF regression was evaluated at the IGP AERONET stations and found to perform well with Pearson correlation coefficients of 0.66 and 0.65, respectively. Using ADRF regression model with MODIS inputs allows for the estimation of ADRF across the IGP for assessing the aerosol impact on ecosystem and crop production. Full article

(This article belongs to the Section Aerosols)

► Show Figures

Figure 1

23 pages, 6119 KiB

Open AccessArticle

Incorporation of Numerical Plume Rise Algorithms in the Lagrangian Particle Model LAPMOD and Validation against the Indianapolis and Kincaid Datasets

by Roberto Bellasio, Roberto Bianconi, Sonia Mosca and Paolo Zannetti

Atmosphere 2018, 9(10), 404; https://doi.org/10.3390/atmos9100404 - 16 Oct 2018

Cited by 10 | Viewed by 4879

Abstract

This paper describes the methodology used to incorporate two numerical plume rise algorithms, one by Janicke and Janicke and another by Webster and Thomson, into the Lagrangian particle model LAPMOD. LAPMOD is fully interfaced with the diagnostic meteorological model CALMET, which is part [...] Read more.

This paper describes the methodology used to incorporate two numerical plume rise algorithms, one by Janicke and Janicke and another by Webster and Thomson, into the Lagrangian particle model LAPMOD. LAPMOD is fully interfaced with the diagnostic meteorological model CALMET, which is part of the widely used CALPUFF modeling system. LAPMOD can also use the meteorological input files produced with the AERMET meteorological processor of the US-EPA recommended model AERMOD. This paper outlines the theory behind the two plume rise algorithms and the details of their implementation in LAPMOD. The paper also provides the results of the evaluation of LAPMOD and its included plume rise algorithms against the well-known Indianapolis and Kincaid SF₆ and SO₂ field studies and tracer experiments. The performance of LAPMOD is successfully evaluated with the Model Evaluation Kit and compared with that of other air quality models. Full article

(This article belongs to the Section Air Quality)

► Show Figures

Figure 1

17 pages, 5919 KiB

Open AccessArticle

Upper Tropospheric Water Vapor Transport from Indian to Sahelian Regions

by Abdoulaye Sy, Bouya Diop, Joël Van Baelen, Christophe Duroure, Yahya Gour and Jean-Luc Baray

Atmosphere 2018, 9(10), 403; https://doi.org/10.3390/atmos9100403 - 16 Oct 2018

Cited by 3 | Viewed by 3459

Abstract

We present a study of upper tropospheric westward transport of air masses coming from the Indian monsoon zone over the period 1998–2008. The objective is to characterize upper tropospheric transport of water vapor from the Indian to Sahelian regions, and to improve the [...] Read more.

We present a study of upper tropospheric westward transport of air masses coming from the Indian monsoon zone over the period 1998–2008. The objective is to characterize upper tropospheric transport of water vapor from the Indian to Sahelian regions, and to improve the understanding of the dynamical mechanisms that govern water vapor variations in West Africa and the interconnections between India and the Sahel, focusing on the direct role of the Indian monsoon region on Sahel tropospheric water vapor and precipitation. The calculations of forward trajectories with LACYTRAJ (LACY TRAJectory code) and humidity fluxes show that a substantial part (40 to 70% at 300 hPa) of trajectories coming from the upper troposphere of the monsoon region crossed the Sahelian region in a few days (3–14 days), and water vapor fluxes connecting these two regions are established when the Indian monsoon begins at latitudes higher than 15° N in its south–north migration. The intensity and orientation of water vapor fluxes are related to the tropical easterly jet, but they are from the east above the high convection zones. Between 1998 and 2008, these fluxes between the 500–300 hPa pressure levels are associated with precipitation in Sahel only if they are from the east and with an intensity exceeding 8 kg·(m·s)⁻¹. Full article

(This article belongs to the Special Issue Stratosphere–Troposphere Exchanges)

► Show Figures

Figure 1

26 pages, 10087 KiB

Open AccessArticle

The Street Air Warming Phenomenon in a High-Rise Compact City

by Xiaoxue Wang, Yuguo Li, Xinyan Yang, Pak Wai Chan, Janet Nichol and Qinglan Li

Atmosphere 2018, 9(10), 402; https://doi.org/10.3390/atmos9100402 - 16 Oct 2018

Cited by 11 | Viewed by 5116

Abstract

The street thermal environment is important for thermal comfort, urban climate and pollutant dispersion. A 24-h vehicle traverse study was conducted over the Kowloon Peninsula of Hong Kong in summer, with each measurement period consisting of 2–3 full days. The data covered a [...] Read more.

The street thermal environment is important for thermal comfort, urban climate and pollutant dispersion. A 24-h vehicle traverse study was conducted over the Kowloon Peninsula of Hong Kong in summer, with each measurement period consisting of 2–3 full days. The data covered a total of 158 loops in 198 h along the route on sunny days. The measured data were averaged by three methods (direct average, FFT filter and interpolated by the piecewise cubic Hermite interpolation). The average street air temperatures were found to be 1–3 °C higher than those recorded at nearby fixed weather stations. The street warming phenomenon observed in the study has substantial implications as usually urban heat island (UHI) intensity is estimated from measurement at fixed weather stations, and therefore the UHI intensity in the built areas of the city may have been underestimated. This significant difference is of interest for studies on outdoor air temperature, thermal comfort, urban environment and pollutant dispersion. The differences were simulated by an improved one-dimensional temperature model (ZERO-CAT) using different urban morphology parameters. The model can correct the underestimation of street air temperature. Further sensitivity studies show that the building arrangement in the daytime and nighttime plays different roles for air temperature in the street. City designers can choose different parameters based on their purpose. Full article

(This article belongs to the Special Issue Urban Design and City Microclimates)

► Show Figures

Figure 1

14 pages, 2049 KiB

Open AccessEditor’s ChoiceArticle

Atmospheric Chemistry of 2-Methoxypropene and 2-Ethoxypropene: Kinetics and Mechanism Study of Reactions with Ozone

by Chen Lv, Lin Du, Narcisse T. Tsona, Xiaotong Jiang and Wenxing Wang

Atmosphere 2018, 9(10), 401; https://doi.org/10.3390/atmos9100401 - 14 Oct 2018

Cited by 2 | Viewed by 4707

Abstract

Rate coefficients at ambient temperature and atmospheric pressure for the reaction of ozone with 2-methoxypropene (2-MPE) and 2-ethoxypropene (2-EPE) were determined in an evacuable 100 L Teflon reaction chamber using absolute and relative rate methods. The product experiments were carried out using a [...] Read more.

Rate coefficients at ambient temperature and atmospheric pressure for the reaction of ozone with 2-methoxypropene (2-MPE) and 2-ethoxypropene (2-EPE) were determined in an evacuable 100 L Teflon reaction chamber using absolute and relative rate methods. The product experiments were carried out using a 50 L Teflon reaction chamber in conjunction with FTIR as the detection technique. The rate coefficients (k in units of cm³ molecule⁻¹ s⁻¹) obtained are 1.18 ± 0.13 × 10⁻¹⁷ and 1.89 ± 0.23 × 10⁻¹⁷ for reactions with 2-MPE and 2-EPE, respectively. The effects of the alkoxy group on the gas-phase reactivity of alkyl vinyl ethers toward ozone are compared and discussed. The major ozonolysis products are methyl acetate, formaldehyde and CO₂ for 2-MPE, and ethyl acetate, formaldehyde and CO₂ for 2-EPE. Possible mechanisms for the two vinyl ethers are proposed based on the observed reaction products. Additionally, atmospheric lifetimes of 32 h and 21 h for 2-MPE and 2-EPE were estimated based on the measured rate constants and the ambient tropospheric concentration of ozone, respectively. The obtained values of the lifetimes indicate that the reaction with ozone is an important loss process for these vinyl ethers in the atmosphere, especially in polluted areas. Full article

(This article belongs to the Special Issue Air Quality in China: Past, Present and Future)

► Show Figures

Graphical abstract

13 pages, 933 KiB

Open AccessBrief Report

Effect of Environmental Measurement Uncertainty on Prediction of Evapotranspiration

by Ling-Hsi Chen, Jiunyuan Chen and Chiachung Chen

Atmosphere 2018, 9(10), 400; https://doi.org/10.3390/atmos9100400 - 12 Oct 2018

Cited by 15 | Viewed by 3327

Abstract

Evapotranspiration (ET) is a typical biological environmental process to influence leaf temperature, crop water requirement, and greenhouse microclimate. Affecting factors of ET include air temperature, air relative humidity, wind speed, solar radiation, longwave radiation, soil moisture, CO₂ concentration, and crop state. In [...] Read more.

Evapotranspiration (ET) is a typical biological environmental process to influence leaf temperature, crop water requirement, and greenhouse microclimate. Affecting factors of ET include air temperature, air relative humidity, wind speed, solar radiation, longwave radiation, soil moisture, CO₂ concentration, and crop state. In this study, two ET models of indoor cultivation commonly adopted in literature were selected to evaluate the effect of the performance of sensors on the model uncertainty. The method of the International Organization for Standardization, Guides to the expression of Uncertainty in Measurement (ISO GUM) was adopted. The result indicated that the performance of leaf area index (LAI) and solar radiation (Is) sensors were primary sources of uncertainty. The uncertainty of ET models due to sensor performance needs to be considered. To ensure the predictive ability for applying the ET model for crops irrigation management and greenhouse environmental control, the improvements in the measurement of environmental variables for calculating ET would be of particular importance. The method of this study can be used for evaluating the uncertainty of ET models that calculate ET based on environmental variables measured by meteorological sensors or the remote sensing technique. Full article

(This article belongs to the Section Biometeorology and Bioclimatology)

► Show Figures

Figure 1

13 pages, 4661 KiB

Open AccessArticle

Local Convection and Turbulence in the Amazonia Using Large Eddy Simulation Model

by Theomar Neves, Gilberto Fisch and Siegfried Raasch

Atmosphere 2018, 9(10), 399; https://doi.org/10.3390/atmos9100399 - 12 Oct 2018

Cited by 10 | Viewed by 4021

Abstract

Using a high resolution model of Large Eddies Simulation (LES), named PALM from PArallel LES Model, a set of simulations were performed to understand how turbulence and convection behave in a pasture and forest sites in Amazonia during the dry and rainy seasons. [...] Read more.

Using a high resolution model of Large Eddies Simulation (LES), named PALM from PArallel LES Model, a set of simulations were performed to understand how turbulence and convection behave in a pasture and forest sites in Amazonia during the dry and rainy seasons. Related to seasonality, dry period presented higher differences of values (40 W m⁻²) and patterns over the sites, while in the wet period have more similar characteristics (difference of −10 W m⁻²). The pasture site had more convection than the forest, with effective mixing and a deeper boundary layer (2600 m). The vertical decrease of sensible heat flux with altitude fed convection and also influenced the convective boundary layer (CBL) height. Regarding the components of turbulent kinetic energy equation, the thermal production was the most important component and the dissipation rate responded with higher growth, especially in cases of greatest mechanical production at the forest surface reaching values up to −20.0. Full article

(This article belongs to the Special Issue Large-Eddy Simulations (LES) of Atmospheric Boundary Layer Flows)

► Show Figures

Figure 1

24 pages, 4608 KiB

Open AccessArticle

Observational Characterization of the Synoptic and Mesoscale Circulations in Relation to Crop Dynamics: Belg 2017 in the Gamo Highlands, Ethiopia

by Thomas T. Minda, Michiel K. van der Molen, Bert G. Heusinkveld, Paul C. Struik and Jordi Vilà-Guerau De Arellano

Atmosphere 2018, 9(10), 398; https://doi.org/10.3390/atmos9100398 - 11 Oct 2018

Cited by 4 | Viewed by 5006

Abstract

The Gamo Highlands in Ethiopia are characterized by complex topography and lakes. These modulate the mesoscale and synoptic scale weather systems. In this study, we analyzed the temporal and spatial variations in weather as function of topography and season and their impact on [...] Read more.

The Gamo Highlands in Ethiopia are characterized by complex topography and lakes. These modulate the mesoscale and synoptic scale weather systems. In this study, we analyzed the temporal and spatial variations in weather as function of topography and season and their impact on potato crop growth. To determine how crop growth varies with elevation, we installed a network of six automatic weather stations along two transects. It covers a 30-km radius and 1800-m elevation difference. We conducted a potato field experiment near the weather stations. We used the weather observations as input for a crop model, GECROS. Data analysis showed large differences between weather in February and May. February is more dominated by mesoscale circulations. The averaged February diurnal patter shows a strong east to southeast lake breezes and, at night, weak localized flows driven by mountain density flows. In contrast, in May, the synoptic flow dominates, interacting with the mesoscale flows. The GECROS model satisfactorily predicted the elevational gradient in crop yield. Model sensitivity experiments showed that belg-averaged precipitation distribution gave the highest yield, followed by exchanging May weather observations with April. Full article

(This article belongs to the Section Biosphere/Hydrosphere/Land–Atmosphere Interactions)

► Show Figures

Figure 1

16 pages, 1008 KiB

Open AccessArticle

A Climatological Study of Western Mediterranean Medicanes in Numerical Simulations with Explicit and Parameterized Convection

by Francesco Ragone, Monica Mariotti, Antonio Parodi, Jost Von Hardenberg and Claudia Pasquero

Atmosphere 2018, 9(10), 397; https://doi.org/10.3390/atmos9100397 - 11 Oct 2018

Cited by 20 | Viewed by 3932

Abstract

The semi-enclosed Mediterranean basin, surrounded by high mountains, is placed in a favorable location for cyclonic storms development. Most of these are extratropical cyclones of baroclinic and orographic origin, but occasionally, some low pressure systems may develop to assume features characteristic of tropical [...] Read more.

The semi-enclosed Mediterranean basin, surrounded by high mountains, is placed in a favorable location for cyclonic storms development. Most of these are extratropical cyclones of baroclinic and orographic origin, but occasionally, some low pressure systems may develop to assume features characteristic of tropical cyclones. Medicanes (MEDIterranean hurriCANES) are infrequent and small-sized tropical-like cyclones. They originate and develop over sea, and are associated with strong winds and heavy precipitations. Proper definitions and classifications for Medicanes are still partially lacking, and systematic climatic studies have appeared only in recent years. In this work, we provide climatologies of Medicanes in the Western Mediterranean basin based on multidecadal runs performed with the Weather Research and Forecasting regional model with different resolutions and setups. The detection of Medicanes is based on a cyclone tracking algorithm and on the methodology of Hart cyclone phase space diagrams. We compare the statistics of Medicanes in the historical period 1979–1998 between runs at a resolution of 11 km with different convective parameterizations and microphysics schemes and one run at a resolution of 4 km with explicitly resolved convection. We show how different convective parameterization schemes lead to different statistics of Medicanes, while the use of different microphysical schemes impacts the length of the cyclone trajectories. Full article

(This article belongs to the Special Issue Mediterranean Tropical-Like Cyclones (Medicanes))

► Show Figures

Figure 1

16 pages, 2659 KiB

Open AccessArticle

Spectroscopic BIL-SFG Invariance Hides the Chaotropic Effect of Protons at the Air-Water Interface

by Simone Pezzotti and Marie-Pierre Gaigeot

Atmosphere 2018, 9(10), 396; https://doi.org/10.3390/atmos9100396 - 11 Oct 2018

Cited by 19 | Viewed by 4067

Abstract

The knowledge of the water structure at the interface with the air in acidic pH conditions is of utmost importance for chemistry in the atmosphere. We shed light on the acidic air-water (AW) interfacial structure by DFT-MD simulations of the interface containing one [...] Read more.

The knowledge of the water structure at the interface with the air in acidic pH conditions is of utmost importance for chemistry in the atmosphere. We shed light on the acidic air-water (AW) interfacial structure by DFT-MD simulations of the interface containing one hydronium ion coupled with theoretical SFG (Sum Frequency Generation) spectroscopy. The interpretation of SFG spectra at charged interfaces requires a deconvolution of the signal into BIL (Binding Interfacial Layer) and DL (Diffuse Layer) SFG contributions, which is achieved here, and hence reveals that even though H

_{3}

O

^{+}

has a chaotropic effect on the BIL water structure (by weakening the 2D-HBond-Network observed at the neat air-water interface) it has no direct probing in SFG spectroscopy. The changes observed experimentally in the SFG of the acidic AW interface from the SFG at the neat AW are shown here to be solely due to the DL-SFG contribution to the spectroscopy. Such BIL-SFG and DL-SFG deconvolution rationalizes the experimental SFG data in the literature, while the hydronium chaotropic effect on the water 2D-HBond-Network in the BIL can be put in perspective of the decrease in surface tension at acidic AW interfaces. Full article

(This article belongs to the Special Issue Physical Chemistry of the Air-Water Interface)

► Show Figures

Graphical abstract

15 pages, 3752 KiB

Open AccessArticle

Re-Examination of the Decadal Change in the Relationship between the East Asian Summer Monsoon and Indian Ocean SST

by Seogyeong Kim, Kyung-Ja Ha, Ruiqiang Ding and Jiangping Li

Atmosphere 2018, 9(10), 395; https://doi.org/10.3390/atmos9100395 - 11 Oct 2018

Cited by 4 | Viewed by 5272

Abstract

This study examines the decadal change in the relationship between two major Indian Ocean (IO) sea surface temperature patterns, namely the Indian Ocean dipole (IOD) and northern IO and the East Asia summer monsoon (EASM) in the early 2000s. In 1991–1999, the former [...] Read more.

This study examines the decadal change in the relationship between two major Indian Ocean (IO) sea surface temperature patterns, namely the Indian Ocean dipole (IOD) and northern IO and the East Asia summer monsoon (EASM) in the early 2000s. In 1991–1999, the former epoch, the interannual variability of EASM was associated with the IOD-like pattern in the original paper and its relationship weakened in 2000–2016. There are two possible causes for this decadal change; stronger land-sea thermal contrast as a local forcing in latter epoch, which may result in the weakening of the relationship between the IO and the EASM. In addition, the influence of El Niño-southern Oscillation (ENSO) on the western North Pacific subtropical high (WNPSH) could be changed depending on the frequency of ENSO. In the 2000s, the intensity of the low frequency (LF)-type ENSO (42–86 months period) events was weaker compared to the former epoch but that of quasi-biennial (QB)-type ENSO (16–36 months period) remained persistent. This could explain that the QB-type ENSO is remote forcing that modulates the change in the relationship between the tropical IO patterns and EASM in the 2000s. Full article

(This article belongs to the Special Issue Monsoons)

► Show Figures

Figure 1

17 pages, 28862 KiB

Open AccessArticle

Vegetation Dynamics and Diverse Responses to Extreme Climate Events in Different Vegetation Types of Inner Mongolia

by Li Na, Risu Na, Jiquan Zhang, Siqin Tong, Yin Shan, Hong Ying, Xiangqian Li and Yulong Bao

Atmosphere 2018, 9(10), 394; https://doi.org/10.3390/atmos9100394 - 11 Oct 2018

Cited by 23 | Viewed by 4893

Abstract

As the global climate has changed, studies on the relationship between vegetation and climate have become crucial. We analyzed the long-term vegetation dynamics and diverse responses to extreme climate changes in Inner Mongolia, based on long-term Global Inventory Monitoring and Modelling Studies (GIMMS) [...] Read more.

As the global climate has changed, studies on the relationship between vegetation and climate have become crucial. We analyzed the long-term vegetation dynamics and diverse responses to extreme climate changes in Inner Mongolia, based on long-term Global Inventory Monitoring and Modelling Studies (GIMMS) NDVI3g datasets, as well as the eight extreme precipitation indices and six extreme temperature indices that are highly correlated with the occurrence of droughts or floods, heat or cold temperature disasters, and vegetation growth in Inner Mongolia. These datasets were analyzed using linear regression analysis, the Hurst exponent index, residual analysis, and the Pearson correlation analysis. The results showed the following: (1) The vegetation dynamical changes exhibited trends of improvement during 1982 to 2015, and 68% of the vegetation growth changes in Inner Mongolia can be explained by climate changes. (2) The extreme precipitation indices exhibited a slight change, except for the annual total wet–day precipitation (PRCPTOT). The occurrence of extreme cold temperatures showed a significant decline, while the occurrence of extreme warm temperatures showed an upward trend in Inner Mongolia. (3) The typical steppe, desert steppe, and forest steppe regions are more sensitive to extreme large precipitation, and the forest regions are more sensitive to extreme warm temperatures. (4) Extreme precipitation exhibits a one-month lagged effect on vegetation that is larger than the same-month effects on the grassland system. Extreme temperature exhibits same-month effects on vegetation, which are larger than the one-month lagged effects on the forest system. Therefore, studies of the relationship between extreme climate indices and vegetation are important for performing risk assessments of droughts, floods, and other related natural disasters. Full article

(This article belongs to the Special Issue Impacts of Air Quality and Climate Change on Vegetation)

► Show Figures

Figure 1

12 pages, 6565 KiB

Open AccessArticle

A Study on Elevated Concentrations of Submicrometer Particles in an Urban Atmosphere

by Hee-Joo Cho, Jia Kang, Dohyeong Kim, Arom Seo, Minhan Park, Hungsoo Joo and Kihong Park

Atmosphere 2018, 9(10), 393; https://doi.org/10.3390/atmos9100393 - 10 Oct 2018

Cited by 6 | Viewed by 3100

Abstract

Mass concentrations of chemical constituents (organics, nitrate, sulfate, ammonium, chloride, and black carbon (BC)) and the number size distribution of submicrometer particles in the ambient atmosphere were continuously measured in urban Gwangju, Korea, during the Megacity Air Pollution Studies (MAPS)-Seoul campaign. Organics (9.1 [...] Read more.

Mass concentrations of chemical constituents (organics, nitrate, sulfate, ammonium, chloride, and black carbon (BC)) and the number size distribution of submicrometer particles in the ambient atmosphere were continuously measured in urban Gwangju, Korea, during the Megacity Air Pollution Studies (MAPS)-Seoul campaign. Organics (9.1 μg/m³) were the most dominant species, followed by sulfate (4.7 μg/m³), nitrate (3.2 μg/m³), ammonium (2.6 μg/m³), and BC (1.3 μg/m³) in submicrometer particles (particulate matter less than 1 μm (PM₁)). The potential source regions of the sulfate were located in the South and East regions of China and South and East regions of Korea, while local sources were responsible for the elevated BC concentration. Diurnal variation showed that concentrations of organics, nitrate, ammonium, chloride, and BC decreased with increasing mixing layer and wind speed (dilution effect), while sulfate and oxidized organics increased possibly due to their strong photochemical production in the afternoon. During the campaign, an elevated mass concentration of PM₁ (PM₁ event) and number concentration (nanoparticle formation (NPF) event) were observed (one PM₁ event and nine NPF events out of 28 days). The PM₁ event occurred with Western and Southwestern air masses with increasing sulfate and organics. Long-range transported aerosols and stagnant meteorological conditions favored the elevated mass concentration of submicrometer particles. Most of the NPF events took place between 10:00 and 14:00, and the particle growth rates after the initial nanoparticle formation were 7.2–11.0 nm/h. The times for increased concentration of nanoparticles and their growth were consistent with those for elevated sulfate and oxidized organics in submicrometer particles under strong photochemical activity. Full article

(This article belongs to the Special Issue Carbonaceous Aerosols: Sources, Physical and Chemical Characterization, and Toxicity)

► Show Figures

Figure 1

17 pages, 1562 KiB

Open AccessArticle

Turbulence Structure in a Stratocumulus Cloud

by Georgios Matheou

Atmosphere 2018, 9(10), 392; https://doi.org/10.3390/atmos9100392 - 10 Oct 2018

Cited by 15 | Viewed by 5850

Abstract

The growth of computing power combined with advances in modeling methods can yield high-fidelity simulations establishing numerical simulation as a key tool for discovery in the atmospheric sciences. A fine-scale large-eddy simulation (LES) utilizing 1.25 m grid resolution and [...] Read more.

The growth of computing power combined with advances in modeling methods can yield high-fidelity simulations establishing numerical simulation as a key tool for discovery in the atmospheric sciences. A fine-scale large-eddy simulation (LES) utilizing 1.25 m grid resolution and

5.12 \times 5.12 {km}^{2}

horizontal domain is used to investigate the turbulence and liquid water structure in a stratocumulus cloud. The simulations capture the observed cloud morphology, including elongated regions of low liquid water path, cloud holes, and pockets of clear air within the cloud. The cloud can be partitioned into two broad layers with respect to the maximum mean liquid. The lower layer resembles convective turbulent structure with classical inertial range scaling of the velocity and scalar energy spectra. The top and shallower layer is directly influenced by the cloud top radiative cooling and the entrainment process. Near the cloud top, the liquid water spectra become shallower and transition to a

k^{- 1}

power law for scales smaller than about

1 km

. Full article

(This article belongs to the Special Issue Large-Eddy Simulations (LES) of Atmospheric Boundary Layer Flows)

► Show Figures

Figure 1

16 pages, 6147 KiB

Open AccessArticle

Empirical Model of Human Thermal Comfort in Subtropical Climates: A First Approach to the Brazilian Subtropical Index (BSI)

by João Paulo Assis Gobo, Marlon Resende Faria, Emerson Galvani, Fabio Luiz Teixeira Goncalves and Leonardo Marques Monteiro

Atmosphere 2018, 9(10), 391; https://doi.org/10.3390/atmos9100391 - 8 Oct 2018

Cited by 11 | Viewed by 4610

Abstract

The bioclimatic well-being of individuals is associated with the environmental characteristics of where they live. Knowing the relationships between local and regional climatic variables as well as the physical characteristics of a given region and their implications on thermal comfort is important for [...] Read more.

The bioclimatic well-being of individuals is associated with the environmental characteristics of where they live. Knowing the relationships between local and regional climatic variables as well as the physical characteristics of a given region and their implications on thermal comfort is important for identifying aspects of thermal sensation in the population. The aim of this study is to develop an empirical model of human thermal comfort based on subjective and individual environmental patterns observed in the city of Santa Maria, located in the state of Rio Grande do Sul, Brazil (Subtropical climate). Meteorological data were collected by means of an automatic meteorological station installed in the city center, which contained sensors measuring global solar radiation, air temperature, globe temperature (via a grey globe thermometer), relative humidity and wind speed and direction. A total of 1720 people were also interviewed using a questionnaire adapted from the model recommended by ISO 10551. Linear regressions were performed to obtain the predictive model. The observed results proposed a new empirical model for subtropical climate, the Brazilian Subtropical Index (BSI), which was verified to be more than 79% accurate, with a coefficient of determination of 0.926 and an adjusted R² value of 0.924. Full article

(This article belongs to the Section Biometeorology and Bioclimatology)

► Show Figures

Figure 1

18 pages, 4846 KiB

Open AccessArticle

An Integrated Method for Factor Number Selection of PMF Model: Case Study on Source Apportionment of Ambient Volatile Organic Compounds in Wuhan

by Fenjuan Wang, Zhenyi Zhang, Costanza Acciai, Zhangxiong Zhong, Zhaokai Huang and Giovanni Lonati

Atmosphere 2018, 9(10), 390; https://doi.org/10.3390/atmos9100390 - 8 Oct 2018

Cited by 19 | Viewed by 4377

Abstract

The positive matrix factorization (PMF) model is widely used for source apportionment of volatile organic compounds (VOCs). The question about how to select the proper number of factors, however, is rarely studied. In this study, an integrated method to determine the most appropriate [...] Read more.

The positive matrix factorization (PMF) model is widely used for source apportionment of volatile organic compounds (VOCs). The question about how to select the proper number of factors, however, is rarely studied. In this study, an integrated method to determine the most appropriate number of sources was developed and its application was demonstrated by case study in Wuhan. The concentrations of 103 ambient volatile organic compounds (VOCs) were measured intensively using online gas chromatography/mass spectrometry (GC/MS) during spring 2014 in an urban residential area of Wuhan, China. During the measurement period, the average temperature was approximately 25 °C with very little domestic heating and cooling. The concentrations of the most abundant VOCs (ethane, ethylene, propane, acetylene, n-butane, benzene, and toluene) in Wuhan were comparable to other studies in urban areas in China and other countries. The newly developed integrated method to determine the most appropriate number of sources is in combination of a fixed minimum threshold value for the correlation coefficient, the average weighted correlation coefficient of each species, and the normalized minimum error. Seven sources were identified by using the integrated method, and they were vehicular emissions (45.4%), industrial emissions (22.5%), combustion of coal (14.7%), liquefied petroleum gas (LPG) (9.7%), industrial solvents (4.4%), and pesticides (3.3%) and refrigerants. The orientations of emission sources have been characterized taking into account the frequency of wind directions and contributions of sources in each wind direction for the measurement period. It has been concluded that the vehicle exhaust contribution is greater than 40% distributed in all directions, whereas industrial emissions are mainly attributed to the west southwest and south southwest. Full article

(This article belongs to the Section Air Quality)

► Show Figures

Figure 1

2 pages, 1182 KiB

Open AccessCorrection

Correction: Fu et al. Long-Term Atmospheric Visibility Trends and Characteristics of 31 Provincial Capital Cities in China during 1957–2016. Atmosphere, 2018, 9, 318

by Weicong Fu, Ziru Chen, Zhipeng Zhu, Qunyue Liu, Jinda Qi, Emily Dang, Minhua Wang and Jianwen Dong

Atmosphere 2018, 9(10), 389; https://doi.org/10.3390/atmos9100389 - 8 Oct 2018

Cited by 1 | Viewed by 3423

Abstract

The authors would like to correct the published article[...] Full article

(This article belongs to the Special Issue Air Quality in China: Past, Present and Future)

► Show Figures

Figure 1

20 pages, 7094 KiB

Open AccessArticle

Chemical Characteristics and Sources of Submicron Particles in a City with Heavy Pollution in China

by Jianlei Lang, Shengyue Li, Shuiyuan Cheng, Ying Zhou, Dongsheng Chen, Yanyun Zhang, Hanyu Zhang and Haiyan Wang

Atmosphere 2018, 9(10), 388; https://doi.org/10.3390/atmos9100388 - 5 Oct 2018

Cited by 22 | Viewed by 4509

Abstract

Submicron particle (PM₁) pollution has received increased attention in recent years; however, few studies have focused on such pollution in the city of Shijiazhuang (SJZ), which is one of the most polluted cities in the world. In this study, we conducted [...] Read more.

Submicron particle (PM₁) pollution has received increased attention in recent years; however, few studies have focused on such pollution in the city of Shijiazhuang (SJZ), which is one of the most polluted cities in the world. In this study, we conducted an intensive simultaneous sampling of PM₁ and PM_2.5 in autumn 2016, in order to explore pollution characteristics and sources in SJZ. The results showed that the average mass concentrations of PM₁ and PM_2.5 were 70.51 μg/m³ and 91.68 μg/m³, respectively, and the average ratio of PM₁/PM_2.5 was 0.75. Secondary inorganic aerosol (SIA) was the dominant component in PM₁ (35.9%) and PM_2.5 (32.3%). An analysis of haze episodes found that SIA had a significant influence on PM₁ pollution, NH₄⁺ promoted the formation of pollution, and SO₄²⁻ and NO₃⁻ presented different chemical mechanisms. Additionally, the results of source apportionment implied that secondary source, biomass burning and coal combustion, traffic, industry, and dust were the major pollution sources for SJZ, accounting for 45.4%, 18.9%, 15.7%, 10.3%, and 9.8% of PM₁, respectively, and for 42.4%, 18.8%, 12.2%, 10.2%, and 16.4% of PM_2.5, respectively. Southern Hebei, mid-eastern Shanxi, and northern Henan were the major contribution regions during the study period. Three transport pathways of pollutants were put forward, including airflows from Shanxi with secondary source, airflows from the central Beijng–Tianjin–Hebei region with fossil fuel burning source, and airflows from the southern North China Plain with biomass burning source. The systematic analysis of PM₁ could provide scientific support for the creation of an air pollution mitigation policy in SJZ and similar regions. Full article

(This article belongs to the Section Aerosols)

► Show Figures

Graphical abstract

15 pages, 4780 KiB

Open AccessArticle

A Two-Decade Anthropogenic and Biogenic Isoprene Emissions Study in a London Urban Background and a London Urban Traffic Site

by M. Anwar H. Khan, Billie-Louise Schlich, Michael E. Jenkin, Beth M. A. Shallcross, Katherine Moseley, Catherine Walker, William C. Morris, Richard G. Derwent, Carl J. Percival and Dudley E. Shallcross

Atmosphere 2018, 9(10), 387; https://doi.org/10.3390/atmos9100387 - 3 Oct 2018

Cited by 25 | Viewed by 5409

Abstract

A relationship between isoprene and 1,3-butadiene mixing ratios was established to separate the anthropogenic and biogenic fractions of the measured isoprene in London air in both urban background (Eltham) and urban traffic (Marylebone Road) areas over two decades (1997–2017). The average daytime biogenic [...] Read more.

A relationship between isoprene and 1,3-butadiene mixing ratios was established to separate the anthropogenic and biogenic fractions of the measured isoprene in London air in both urban background (Eltham) and urban traffic (Marylebone Road) areas over two decades (1997–2017). The average daytime biogenic isoprene mixing ratios over this period reached 0.09 ± 0.04 ppb (Marylebone Road) and 0.11 ± 0.06 ppb (Eltham) between the period of 6:00 to 20:00 local standard time, contributing 40 and 75% of the total daytime isoprene mixing ratios. The average summertime biogenic isoprene mixing ratios for 1997–2017 are found to be 0.13 ± 0.02 and 0.15 ± 0.04 ppb which contribute 50 and 90% of the total summertime isoprene mixing ratios for Marylebone Road and Eltham, respectively. Significant anthropogenic isoprene mixing ratios are found during night-time (0.11 ± 0.04 ppb) and winter months (0.14 ± 0.01 ppb) at Marylebone Road. During high-temperature and high-pollution events (high ozone) there is a suggestion that ozone itself may be directly responsible for some of the isoprene emission. By observing the positive correlation between biogenic isoprene levels with temperature, photosynthetically active radiation and ozone mixing ratios during heatwave periods, the Cobb-Douglas production function was used to obtain a better understanding of the abiotic factors that stimulate isoprene emission from plants. Other reasons for a correlation between ozone and isoprene are discussed. The long-term effects of urban stressors on vegetation were also observed, with biogenic isoprene mixing ratios on Marylebone Road dropping over a 20-year period regardless of the sustained biomass levels. Full article

(This article belongs to the Special Issue Biogenic Emissions to the Atmosphere)

► Show Figures

Figure 1

24 pages, 5850 KiB

Open AccessArticle

Effects of Atmospheric Dry Deposition on External Nitrogen Supply and New Production in the Northern South China Sea

by Hung-Yu Chen and Shih-Zhe Huang

Atmosphere 2018, 9(10), 386; https://doi.org/10.3390/atmos9100386 - 3 Oct 2018

Cited by 13 | Viewed by 4248

Abstract

The South China Sea (SCS) is one of the world’s largest oligotrophic marginal seas. Increases in biomass and primary production in the surface layer of the northern SCS are affected by anthropogenic aerosol use among north Asian peoples. The seasonal variation of dry [...] Read more.

The South China Sea (SCS) is one of the world’s largest oligotrophic marginal seas. Increases in biomass and primary production in the surface layer of the northern SCS are affected by anthropogenic aerosol use among north Asian peoples. The seasonal variation of dry deposition and its contribution to new production in the ocean are vital to determining the effect that such dry deposition has on the biogeochemical cycle of the SCS. This study collected 240 samples of total suspended particles at Dongsha Island in the northern SCS from April 2007 to March 2009; the major ions and water-soluble nitrogen species in the samples were analyzed. The analysis results indicated that the concentration distributions of major water-soluble ions and nitrogen species in total suspended particles exhibited significant seasonal (source) variation. The north-east monsoon seasons (autumn to spring) brought relatively high concentrations because most air masses during this period arrived from the northern continental region. We found that the concentration of nitrogen species shows a latitude distribution, gradually decreasing from north to south. In addition, this study also discovered that the ratio of organic nitrogen to total dissolved or water-soluble nitrogen also varies in a similar manner, resulting in a concentration of <20% for locations north of 30° N and >30% for those south of 30° N. Aerosols at Dongsha Island mainly comprised sea salt; however, significant chloride depletion was observed during the north-east monsoon season. The molar ratio of NH₄⁺ to non–sea salt (NSS) sulfate (nss-SO₄²⁻) was 0.8, indicating that the amount of artificially produced NH₄⁺ in the region was insufficient for reaction with nss-SO₄²⁻. Therefore, NH₄⁺ was mainly present in the form of NH₄HSO₄. The fluxes of water-soluble inorganic nitrogen (WSIN) and water-soluble organic nitrogen (WSON) within the region were 23 ± 13 and 27 ± 15 mmol m⁻² y⁻¹, respectively. The new production converted from atmospheric water-soluble nitrogen species in the northern SCS was estimated to be 0.52–0.81 mmol C m⁻² d⁻¹. This flux made about 5.6–8.7% (the global average was about 3.5%) contribution to the primary production (9.24 mmol C m⁻² d⁻¹) of the SCS surface water. This result indicates that the ocean’s external nitrogen supply, provided by anthropogenic aerosols, is vital for the biogeochemical cycle in Asian marginal seas, particularly the northern SCS. Full article

(This article belongs to the Special Issue Atmospheric Nutrients: Sources, Processes and Impact on Terrestrial and Marine Ecosystems)

► Show Figures

Figure 1

60 pages, 790 KiB

Open AccessReview

Climate Change and Water-Related Infectious Diseases

by Gordon Nichols, Iain Lake and Clare Heaviside

Atmosphere 2018, 9(10), 385; https://doi.org/10.3390/atmos9100385 - 2 Oct 2018

Cited by 46 | Viewed by 21735

Abstract

Background: Water-related, including waterborne, diseases remain important sources of morbidity and mortality worldwide, but particularly in developing countries. The potential for changes in disease associated with predicted anthropogenic climate changes make water-related diseases a target for prevention. Methods: We provide an [...] Read more.

Background: Water-related, including waterborne, diseases remain important sources of morbidity and mortality worldwide, but particularly in developing countries. The potential for changes in disease associated with predicted anthropogenic climate changes make water-related diseases a target for prevention. Methods: We provide an overview of evidence on potential future changes in water-related disease associated with climate change. Results: A number of pathogens are likely to present risks to public health, including cholera, typhoid, dysentery, leptospirosis, diarrhoeal diseases and harmful algal blooms (HABS). The risks are greatest where the climate effects drive population movements, conflict and disruption, and where drinking water supply infrastructure is poor. The quality of evidence for water-related disease has been documented. Conclusions: We highlight the need to maintain and develop timely surveillance and rapid epidemiological responses to outbreaks and emergence of new waterborne pathogens in all countries. While the main burden of waterborne diseases is in developing countries, there needs to be both technical and financial mechanisms to ensure adequate quantities of good quality water, sewage disposal and hygiene for all. This will be essential in preventing excess morbidity and mortality in areas that will suffer from substantial changes in climate in the future. Full article

(This article belongs to the Special Issue Impacts of Climate Change on Human Health)

14 pages, 5945 KiB

Open AccessArticle

Polar Cooling Effect Due to Increase of Phytoplankton and Dimethyl-Sulfide Emission

by Ah-Hyun Kim, Seong Soo Yum, Hannah Lee, Dong Yeong Chang and Sungbo Shim

Atmosphere 2018, 9(10), 384; https://doi.org/10.3390/atmos9100384 - 1 Oct 2018

Cited by 13 | Viewed by 6860

Abstract

The effects of increased dimethyl-sulfide (DMS) emissions due to increased marine phytoplankton activity are examined using an atmosphere-ocean coupled climate model. As the DMS emission flux from the ocean increases globally, large-scale cooling occurs due to the DMS-cloud condensation nuclei (CCN)-cloud albedo interactions. [...] Read more.

The effects of increased dimethyl-sulfide (DMS) emissions due to increased marine phytoplankton activity are examined using an atmosphere-ocean coupled climate model. As the DMS emission flux from the ocean increases globally, large-scale cooling occurs due to the DMS-cloud condensation nuclei (CCN)-cloud albedo interactions. This cooling increases as DMS emissions are further increased, with the most pronounced effect occurring over the Arctic, which is likely associated with a change in sea-ice fraction as sea ice mediates the air-sea exchange of the radiation, moisture and heat flux. These results differ from recent studies that only considered the bio-physical feedback that led to amplified Arctic warming under greenhouse warming conditions. Therefore, climate negative feedback from DMS-CCN-cloud albedo interactions that involve marine phytoplankton and its impact on polar climate should be properly reflected in future climate models to better estimate climate change, especially over the polar regions. Full article

(This article belongs to the Special Issue Aerosol-Cloud Interactions)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Atmosphere, Volume 9, Issue 10 (October 2018) – 48 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI